Going through the cutscene list, all of the enemies that are not of the five races or primals have the animation, so, despite looking void-ish, with the black and purple smoke and bits of aether, I'm with you that it might just be generic. Even the Sahagin has it - a primal-tempered spoken, as does Aiatar, a normal scalekin as far as we know, and finally Miser's Mistress, who I don't see having any connection the void; not a single voidsent appears in the Aurum Vale.
